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Optical tuning behavior of Al 0.25 Ga 0.75 As/GaAs HBT oscillators with transparent ITO emitter contacts
Author(s) -
Freeman P. N.,
Karaküçük M.,
Bhattacharya P. K.
Publication year - 1995
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/mop.4650090402
Subject(s) - heterojunction bipolar transistor , common emitter , optoelectronics , materials science , ohmic contact , capacitance , diffusion capacitance , varicap , oscillation (cell signaling) , indium tin oxide , electrical engineering , voltage , bipolar junction transistor , transistor , electrode , nanotechnology , chemistry , layer (electronics) , engineering , biochemistry
Optical tuning experiments were performed on an Al 0.25 Ga 0.75 As/GaAs HBT oscillator operating at 6 GHz. The HBT was fabricated with a transparent emitter ohmic contact made of indium‐tin‐oxide (ITO) to allow light input through the top of the device. Under direct illumination of the base and base‐collector depletion regions, optical tuning was observed with an increase in oscillation frequency of up to 25 MHz. The observed increase in frequency is attributed to a shift in resonance due to a decrease in the base‐emitter junction capacitance of the HBT under optical illumination. This effect is verified using detailed device and circuit modeling techniques. © 1995 John Wiley & Sons, Inc.